EXCLUSIVE: A rebranding of Immigration and Customs Enforcement (ICE)’s investigative unit, purportedly due to "undue toxicity" that ICE faces from some on the left, is apparently causing some frustration within the agency -- with a top official in its separate branch promising employees that it will avoid "political theater."

Homeland Security Investigations (HSI), which is part of ICE and conducts federal criminal investigations involving transnational crime, rolled out a standalone website on Tuesday that shakes off the ICE branding.

ICE acting director Patrick Lechleitner told the Washington Post that the "independent branding" allows HSI "to work without the undue toxicity that in some places comes with the ICE moniker."

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The rebranding comes amid continued and fierce resistance from some on the left over ICE’s mission, through its Enforcement and Removal Operations (ERO) wing, to arrest and deport illegal immigrants. 

‘Sanctuary’ jurisdictions limit local law enforcement cooperation with ICE, while a number of Democrats in Congress have backed the "Abolish ICE" movement. The Biden administration itself sought to shut down ICE deportations after entering office, but was blocked by a federal judge. Major cities like New York City, Los Angeles and Chicago refuse to work with ICE in some aspects of its mission. 

With that left-wing opposition in mind, being associated with ICE can have negative effects on investigators who aren't dealing with immigration directly, the ICE chief said. 

"We’re not a political organization. We’re a law enforcement, national security, public safety agency. However, it was affecting HSI’s ability to conduct operations and investigations," Lechleitner told the Post. 

He stressed, however, that it would still remain part of ICE. But the new standalone website made little mention of the agency. The rollout was accompanied by a slick video posted on X, which told viewers to "Please allow us to reintroduce ourselves" -- a possible nod to rapper Jay Z’s "Public Service Announcement."

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But the rebranding appears to have caused some frustration at the ERO side of ICE, which unlike its neighbor is keeping its ICE branding. In an internal email to ERO employees, seen by Fox News Digital, ERO Executive Associate Director Daniel Bible noted the HSI rebrand, but made it clear that ERO would not be following suit.

"HSI’s decision was made in what its leadership believes is best for the program," he said. "Similarly, [ERO] decisions are guided by what is believed to be the best for it operational and programmatically. ERO has and always will continue to focus its decision making on its most important attribute: each of you."

He then promised that there would not be a "wholesale rebranding of ERO."

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"ERO operates with professionalism, honor, compassion and integrity. Our mission will not be swayed by political theater or media rhetoric and our identity will remain steadfast," he said in the defiant email.

Bible went on to list off recent successes by the agency, including Operation Speed Race -- which nabbed 216 criminals involved in drug trafficking – and Operation Night Guard which resulted in the arrest of 171 murderers and predators. He also highlighted a separate operation that resulted in the arrest of 275 sex offenders.

"As we move forward together, and as ERO’s mission evolves and matures, I will continue to champion the ERO brand, to advocate for the brave men and women of ERO and to push for changes to policy and structure to give ERO the operating space to exercise its criminal and civil immigration authorities," Bible said.

"Let me reiterate, I am proud to be part of the ICE and ERO family, and I know each of you are as well."

The frustration comes amid an ongoing crisis at the border which has spilled out into cities and towns across the country. ICE itself has had its hands full, recently arresting a slew of criminal illegal immigrants -- including child sex offenders -- who had been arrested by local jurisdictions but then released onto the streets despite ICE’s pleas for cooperation.

The Biden administration has caused controversy by narrowing ICE's enforcement priorities and placing additional limits on where agents can make arrests, reducing deportations significantly from Trump-era levels. DHS Secretary Alejandro Mayorkas has said that illegal presence in the U.S. is now not by itself a basis to begin enforcement against an illegal immigrant. But the administration has claimed that its actions have allowed it to focus on public safety and national security threats with the limited resources available to it, while calling for additional resources from Congress.

In response to the rebranding, RJ Hauman, President of the National Immigration Center for Enforcement (NICE) and visiting adviser at The Heritage Foundation, claimed that the overhaul was part of an anti-enforcement agenda from the administration.

"Through countless policy memos, pilot programs, and using resources improperly, the Biden administration has effectively dismantled the ability of ICE to arrest, detain, and remove illegal aliens in accordance with the law," he said. "But they don’t only hate the rule of law, they despise the agency itself, especially its core law enforcement unit — ERO."

"Rather than standing shoulder to shoulder with the brave men and women of ERO and pushing back against false ICE narratives and absurd operational requests, current leaders are siding with a unit who thinks they’re above enforcing immigration laws, and would rather do customs. Detaining and removing illegal aliens on a proper scale should take precedent over finding counterfeit NFL jerseys and returning stolen antiquities," he added.